1. Field of the Invention
The present invention relates to a fuel control device for internal-combustion engines and, more particularly, to a fuel control device which enables the correction of a change with time in a hot-wire intake sensor used for fuel control thereof.
2. Description of the Prior Art
A hot-wire intake sensor used in an internal-combustion engine is subjected to a characteristic change caused by deposits of substances on the surface of a hot wire, resulting in such problems as an error in the quantity of fuel fed into the engine, degraded exhaust gases, and in lowered operation performance.
To cope with such problems one practice has been to heat the hot wire up to temperatures over a normal working temperature while the engine is at a stop, in an attempt to burn off the deposits on the hot-wire surface.
A method of this burn-off is described in Laid-Open Japanese Patent No. Sho 54-76182.
It, however, has become clear that performing the burn-off with appropriate frequency is not sufficient to remove the deposits completely, and, moreover, a characteristic change is accumulated, giving an adverse effect to an exhaust gas level and operation performance. That is, there is such a disadvantage that, of components attaching on the hot wire, a substance which is noncombustible at a burn-off temperature accumulates with the lapse of operating time, thereby promoting a change in the characteristic of the intake sensor.